Summary%20on%20WG%202

1
Summary on WG 2

• LINAC Technology

2
Discussion on Technical issues

• Definition of work package leaders
• Work package leaders will be contacted by L.
  Lilje next week

3
Program

• Danilo Barni Module, Tuner (20 min)
• AFTERNOON session (Coffe Break 16.00)
• Add. information available on request by
• Leaks in tests - Detlef Reschke
• Cleanroom Quality control - Axel Matheisen
• Flange designs - Kirsten Zapfe
• Coupler Design and Processing - Terry Garvey /
  W.-D. Moeller
• HOM and Pickup - Wolf-Dietrich Moeller
• Experience Module Assembly Rolf Lange
• Active tuning - Lutz Lilje/Stefan Simrock
• Priority and effort estimation, definition of
  Work packages
• Presentation of itemized priority list - L.Lilje
  / D.Reschke (20 min)
• Discussion on estimation of the effort needed to
  address technical issues and priority ranking
• Definition of Work packages
• Discussion Distribution of Work packages
• Preparation of the Summary

• MORNING session
• RD Session 9.00-10.00
• H. Padamsee DESY EP single cell cavity sent to
  Cornell - various treatments and results
  (20min)
• H. Padamsee 550 RRR russian Nb single cell cavity
  high gradients results with thermometry (20min)
• L. Lilje High gradients in TESLA nine-cell
  cavities (20min)
• General Talk 10.00-11.20. (coffee break)
• Paolo Pierini - Design consideration for
  accelerator reliability (30 min)
• Cristian Magne Cold BPM - (30 min)
• Overview technical issues related to
  superconducting accelerating modules
• 11.20-12.00 Lutz Lilje String, Cavities, Coupler,
  HOM , Clean room assembly - (40 min)

4
L. Lilje

• High power test
• Piezo compensation

5
High Power Test of an EP nine-cell cavity
HERA plant
Calib. Measurement

• 5 Hz, 500 us fill, 800us flat-top
• Feed-forward only
• No piezo compensation at the moment
• 33-35 MV/m with no interruption related to
  cavity-coupler-klystron since more than 130 hours
• 2 cryo problems at 95 and 130 hours resulting
  from connection to the HERA plant
• Cryo shutdown right now due to problem of
  impurities in He circuit (from HERA plant)
• (scheduled calibration measurement at 65 hours
  shown in the plot)
• Very low activity in the high power coupler,
  temperature levels o.k. for 5 Hz
• No field emission observable

6
Frequency stabilization at 35 MV/m
Blue With piezo Red Without piezo Frequency
detuning of 1000 Hz compensated with resonant
excitation of a mechanical cavity resonance at
230 Hz. NOTE This is rather an demonstration of
the capability of active tuning. Application in a
real machine is probably difficult/impossible.
7
Hassan Padamsee

• RF Critical field of niobium
• In-situ Bakeout

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Cornell Results
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P. Pierini

• Reliability
• Bottom-up approach is more reasonable than
  Top-down (complexity generates wrong results)

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Warning/2

• Formal mathematical and statistical methods can
  be applied to measure and assess reliability
  characteristics of components, but the associated
  uncertainties are high, leading to reliability
  estimates with limited credibility
• (...) the role of mathematical and statistical
  methods in reliability engineering is limited,
  and appreciation of the uncertainty is important
  in order to minimize the chances of performing
  inappropriate analysis and of generating
  misleading results. () practical engineering
  must take precedence in determining the causes of
  problems and their solutions PDT OConnor

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However

• There exist design principles to achieve a
  reliable system
• Derating Operate components below max rating
• Redundancy Provide more components with a given
  function
• Fault Tolerance Component failure do not imply
  system failure
• Mathematical and statistical methods for
  reliability assessment teach us that the
  reliability of a complex system depends
• not only by the component specifications
  (MTBF/MTTR),
• but also, even more importantly, by the logical
  and functional connections (role of redundancies
  and spares)
• In other words, proper planning of redundancies
  allows building reliable systems out of
  moderately reliable components

13
C. Magne

• Cold BPM design
• Dark current monitor
• Resolution needed for cavity dark current 100 nA?

14
Cold BPM for TTF2

• Tesla prototype
• - low beam impedance
• cooling to 2K without strain

- Low beam coupling impedance reduces the beam
break-up forces and minimizes the cryogenic
heat-load due to resonances. - The (axial)
geometry is favorable to cooling to 2K without
strain. - The dimensions are small. - The design
is adapted to UHV dust-free conditions. - The
mechanics is relatively simple to machine
(lathe?precision of axial sym.) Ability
to measure sum signal and dark current
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Dark Current Monitor laboratory test
Fmono 1.3 GHz Fdip 2.6 GHz
  An aluminium prototype has been fabricated to
study the optimum antenna design. - Network
analyser - testbench
Alu prototype
Electronics (analog) - One unit (refurbished) is
avalaible - Need to build 1 (or 2?) more
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Discussion on technical issues

• Leaks in tests - Detlef Reschke
• Flange designs - Kirsten Zapfe
• Cleanroom Quality control - Axel Matheisen
• Coupler Design and Processing - Terry Garvey /
  W.-D. Moeller
• HOM and Pickup - Wolf-Dietrich Moeller
• Experience Module Assembly Rolf Lange
• Active tuning - Lutz Lilje/Stefan Simrock

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Work package list
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Work group leader tasks

• Initiate decision-making process
• Make a detailed list/ programme as soon as
  possible
• Estimation of time required and effort to do this
  (money, manpower)
• List of open questions
• Prepare status report for end of August
• Report will be made available preferrable through
  EDMS (Instructions will be send by Axel Matheisen
  asap)
• Discussion during next TESLA Meeting

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Thanks to all contributors for the very useful
discussion and the will to take over the work
!!!!